Diamondback Energy Inc. has agreed to buy Energen Corp. in an all-stock deal valued at about $9.2 billion, including Energen's net debt of $830 million as of June, the companies said late Tuesday. Under the terms of the deal, Energen shareholders would receive 0.6442 shares of Diamondback common stock, representing an implied value to each Energen shareholder of $84.95 a share based on the closing price of Diamondback stock on Monday. The transaction was unanimously approved by each company's board of directors, they said in a statement. The deal would make Diamondback one of the largest independent energy companies in West Texas's Permian basin, and increase by 57% Diamondback's net acreage in the one of the most prolific U.S. "tight" oil and gas regions. The deal would be "immediately accretive" in 2019 on earnings per share, cash flow per share, net asset value, and other key metrics, the companies said. Shares of Diamondback were halted, and ended the regular trading day up 1.4%; Energen shares rallied 7.6%, and the shares ended the regular session up 2.5% at $73.14.

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